The invention relates to a bellows for a vacuum capacitor with a uniform electrically conductive layer as well as to a method for the production of the bellow.
Bellows structures are used in variable vacuum capacitors where, as a mechanical part, in addition to electrical properties, they must fulfill a sealing function. They must be HF-conductive, i.e., have good high-frequency conductivity and withstand a mechanical and thermal continuous load, which represent the long-time properties of a vacuum capacitor.
Over time, known bellows of bronze and other alloys experience material fatigue and often do not fulfill the requirements with respect to life span.
JP-06204082-A discloses a vacuum capacitor that uses a stainless steel bellows with a copper or silver coating to improve the electrical properties. As known, previously used processes for coating the bellows result in very different layer thicknesses because of inhomogeneous flow distribution during the coating process. These uneven layer thicknesses are disadvantageous with respect to electrical loading capacity as well as life span, since the locally elevated bending forces during application of mechanical loads result in material fatigue or breakage, first of the layer and later of the carrier material.
It is the objective of the invention to describe a bellows for a vacuum capacitor that consists of a carrier material and at least one applied layer, of which at least one is constructed in an electrically conductive manner and is characterized by the most uniform layer thickness possible. The homogeneity of the layer achieves a longer life span. Another objective of the invention is the production of such a bellows.
According to the invention, this objective is realized with a bellows for a vacuum capacitor and with a method for producing the bellows for a vacuum capacitor.